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incorporate the spirit of change proposed by @DanielSidhion at https://github.com/NixOS/nixpkgs/pull/277534#discussion_r1450778530

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Chris McDonough 2024-01-12 22:15:43 -05:00
parent 32638686d1
commit 25b2c3a0cc
1 changed files with 6 additions and 19 deletions
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25
doc/build-helpers/trivial-build-helpers.chapter.md
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@ -62,14 +62,16 @@ This sets [`allowSubstitutes` to `false`](https://nixos.org/nix/manual/#adv-attr
Nixpkgs provides the following functions for producing derivations which write text into the Nix store: `writeTextFile`, `writeText`, `writeTextDir`, `writeScript`, `writeScriptBin`, `writeShellScript`, and `writeShellScriptBin`.
`writeText`, `writeTextDir`, `writeScript`, and `writeScriptBin` are convenience functions over `writeTextFile`.
`writeText`, `writeTextDir`, `writeScript`, `writeScriptBin`, `writeShellScript`, and `writeShellScriptBin` are convenience functions over `writeTextFile`.
These are useful for creating files from Nix expressions, which may be scripts or non-executable text files.
The result of each of these functions will be a derivation. When you coerce the resulting derivation to text, it will evaluate to the *store path*. Importantly, it will not include the destination subpath produced by the particular function. So, for example, given the following expression:
Each of these functions will cause a derivation to be realized. When you coerce the result of each of these functions to a string, it will evaluate to the *store path* of this derivation.
:::: {.warning}
Some of these functions will put the resulting files within a directory inside the derivation output. If you need to refer to the resulting files somewhere else in Nix code, remember to append the path to the file For example:
```nix
my-file = writeTextFile {
name = "my-file";
text = ''
@ -77,23 +79,12 @@ my-file = writeTextFile {
'';
destination = "/share/my-file";
}
```
If `my-file` is coerced to text, it will resolve to `/nix/store/<store path>`, like any other derivation. It will *not* evaluate to `/nix/store/<store path>/share/my-file`. So to use it elsewhere, as an example (in this case, within a shell script you're writing in a Nix expression via `writeShellScript`), you might do:
```nix
writeShellScript "evaluate-my-file.sh" ''
cat ${my-file}/share/my-file
'';
```
This will produce the desired result. However, the following will not, it will fail because the store path is a directory, and is not the `my-file` file.
```nix
writeShellScript "evaluate-my-file.sh" ''
cat ${my-file}
'';
```
::::
### `writeTextFile` {#trivial-builder-writeTextFile}
@ -180,10 +171,6 @@ writeTextFile {
```
:::
::: {.note}
The commands `writeText`, `writeTextDir`, `writeScript`, `writeScriptBin`, `writeShellScript`, and `writeShellScriptBin` documented below are convenience functions that wrap `writeTextFile`.
:::
### `writeText` {#trivial-builder-writeText}
Writes a text file to the store